// server/budget-mutex.js — In-memory mutex for budget-modifying operations
// Prevents race conditions when multiple requests check availability simultaneously

let _lock = null;

async function acquireBudgetLock() {
  while (_lock) await _lock;
  let resolve;
  _lock = new Promise(r => { resolve = r; });
  return () => { _lock = null; resolve(); };
}

module.exports = { acquireBudgetLock };